This invention relates generally to producing optical fiber.
A conventional method of producing optical fiber comprises the following steps: drawing the fiber from a heated end of a preform, cooling the fiber, applying one or more polymeric coatings to the fiber and winding the coated fiber onto a storage bobbin. Fiber and coating diameters and drawing tensions are controlled during such a method.
During the start of the process contaminants may enter the coating system and this may not be detected until after the bobbin has been filled, leading to considerable waste.
In order to avoid this problem in the present invention rather than wind the fiber directly onto the storage bobbin it is initially wound about the storage bobbin and onto another bobbin. When desired drawing conditions are reached, the fiber is cut between the bobbins and the drawn fiber is wound onto the storage bobbin. The fiber wound onto the other bobbin may then be tested whilst drawing continues. If the test results are unsatisfactorily appropriate remedial action may be taken.
The invention provides take-up apparatus for drawn optical fiber comprising:
first supporting means for supporting a first bobbin about a first axis; first rotating means for rotating such a first bobbin, when supported by said first supporting means, about said first axis; second supporting means for supporting a second bobbin about a second, different axis; second rotating means for rotating such a second bobbin, when supported by said second supporting means, about said second axis; guide means for guiding a drawn optical fiber about a first bobbin when supported by said first supporting means and to a second bobbin when supported by said second supporting means; means for controlling the relative rates of rotation provided by the first and second rotating means; and means for causing drawn fiber attached at a leading end thereof to a first bobbin when supported by said first supporting means and rotated by said first rotating means to be wound onto such a bobbin in a plurality of layers.
The invention also includes an optical fiber production line having apparatus as defined in the last preceding paragraph.
The invention also includes apparatus as defined in the last but one preceding paragraph having a said first bobbin supported by said first supporting means and a said second bobbin supported by said second supporting means. Advantageously, the first bobbin is of greater capacity than said second bobbin.
Preferably the first and second axes are substantially parallel.
The first supporting means may be adapted to reciprocate a first bobbin, when supported thereby, along said first axis. In this case, typically the supporting means comprises a member slidably mounted for reciprocating movement along said first axis.
The second supporting means may be adapted to reciprocate a second bobbin, when supported thereby, along said second axis. In this case preferably the second support means comprises a support fixedly mounted to said member for reciprocating movement therewith.
Advantageously the support is located above said first supporting means.
The invention also includes a method of drawing optical fiber including guiding the drawn fiber about a first bobbin to a second bobbin, rotating said bobbins to wind the fiber about the first bobbin and onto the second bobbin during initial drawing of the fiber, and subsequently cutting the fiber between the bobbins and winding the drawn fiber onto the first bobbin.
The method may include testing fiber wound onto the second bobbin whilst winding fiber onto the first bobbin.
The method may include controlling the tension of the fiber between the first and second bobbins during the step of winding the fiber about the first bobbin and onto the second bobbin by controlling the relative rates of rotation of said bobbins.
The method preferably includes after the cutting step, adhering the upstream cut end of fiber to the surface of a hub of the first bobbin. In this regard the method may include providing a double-sided adhesive tape about the hub of the first bobbin and adhering the upstream cut end of the fiber to the tape. Alternatively, the method may include providing a tape which is adhesive on one side only, adhesive side out about the hub of the first bobbin and adhered to itself, and adhering the upstream cut end of the fiber to the tape.